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Getting a 90 volt dc motor running?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by L6steel, Feb 12, 2004.

  1. L6steel


    Sep 23, 1999
    I have a 90 volt dc motor that I'm built a horizontal lap sander with. All I need to do is get the thing wired.
    My question is, what do I need to hook it up?
    I have a dc motor controller but I got to thinking.
    This is a single speed geared motor so why waste a variable speed controller on it.
    Can't I just wire it up with a rectifier and transformer and off and on switch?
    Anyone have experiance with this type of thing or know where I can find the items needed to rig it?
    Thanks up front folks!!
  2. Sando


    Jul 4, 2002

    I won't pretend to know the answer from experience or a swell list of academic credentials. But I'd say yes without worry to using a transformer and bridge rectifier, given that all of them are rated for that much current. A large electolytic capacitor might help smooth the current more, but I don't think that's important with motors. (I hope an electronics guy pipes in, because this is a great idea.)

    In fact I wish I'd thought of this.

    I have hooked mine up to a car battery. Runs quite well.

  3. Mike Hull

    Mike Hull

    Nov 25, 2000
    I have a 90VDC gearmotor out in the shop. It was/is connected to VS controls. It was hooked up that way from the factory, on the equipment it was in. So you might just want to use that DC control. :confused:
  4. Doc Hollywood

    Doc Hollywood

    Jan 24, 2003
    If one of you has a burned out controller (burned componenets....not board), I would be happy to reverse engineer the thing for you and duplicate it. This would make replacement alot cheaper since the components are pennies to a dollar or so, and the boards are easy enough to make.

    I am not sure how the transformer/rectifier thing would work, but sounds plausible to me.

  5. Daniel Koster

    Daniel Koster www.kosterknives.com Knifemaker / Craftsman / Service Provider

    Oct 18, 2001
    Doc - are you saying you could duplicate the board at cost + your labor?

    If so, I have a spare VDC controller board I could send you (will need a week to get it ready first).

    Do you know if it's possible to increase the amperage it can handle? (from 11 to say....16?) Just curious...maybe it's too difficult...
  6. Doc Hollywood

    Doc Hollywood

    Jan 24, 2003
    I can look at it and see if I can up the ante on current capability. It should not be too difficult, but without looking I don't know.

    You can call me this weekend, and we can discuss the whole thing...256.883.8611 and ask for Doc. The cost should be cheap enough, and if I can get more than one to make at a time the cost should get cheaper as I can etch the boards in multiples.....

    If you want to up the power though we may have to do some back and forth on the thing till we get the bugs worked out, but it shouldn't be too bad.

  7. Daniel Koster

    Daniel Koster www.kosterknives.com Knifemaker / Craftsman / Service Provider

    Oct 18, 2001
    email sent.
  8. rlinger


    Mar 29, 2002

    You'll need a hefty transformer to provide the HP. Provided, with a full wave rectifier it will work but your DC voltage will be something greater than the transformers AC RMS output. Use the DC motor drive instead. You'll like being able to make the grinder crawl at times.


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